It has been known in arthroscopic surgical procedures, to enter a surgical site, for example a knee joint, with an elongate entry tool, such as a trocar, sheathed in a snug fitting outer cannula. Thereafter the entry tool is removed, leaving the entry end of the cannula at the surgical site and the other end of the cannula protruding from the patient. Thereafter, one or more additional elongate surgical tools, such as an arthroscope or obturator can, in desired sequence, be alternately inserted through the cannula to reach the surgical site.
Further, it is known to equip the cannula for connection to an irrigation liquid source for injection of irrigation liquid therethrough into the surgical site, or to a pressure gas source for creating an inflated chamber at the surgical site, or to a suction source for removing flowable material from the surgical site.
In each instance, the cannula extending into the surgical site acts as a conduit of access to the surgical site from outside the body in the patient and permits a variety of surgical procedures to be performed without requiring more than the very small incision needed to insert the distal end of the cannula.
In prior devices of this type, the outer end of the cannula may be provided with a manually actual locking device engageable with a connector on the tool for axially fixing the tool within the sleeve.
In one such prior locking device, a threaded member must be rotated with respect to the rest of the cannula to lock and unlock a tool with respect to the cannula. However, some surgeons have confused the lock and unlock rotation directions. Further, the threaded member have become slippery during surgery and require extra care to lock and unlock. Further, a surgeon may fail to fully rotate the threaded member and thus need to repeat the rotation. It may be difficult to achieve locking and unlocking with one hand.
In a subsequent prior art device, namely one shown in U.S. Pat. No. 5,171,245 assigned to the Assignee of the present invention, locking and unlocking may be achieved with one hand. However, the locking mechanism is relatively complex structurally and hence expensive to produce.
Accordingly, in a continuing effort to improve on apparatus of this general kind, the present invention was developed.
Accordingly, the objects and purposes of this invention include provision of such an improved locking cannula and tool arrangement.
Further objects and purposes of the invention will be apparent to persons acquainted with apparatus of this general type upon reading the following specification and inspecting the accompanying drawings.